Need help please!!!!! Any cadillac technicians!!!!

So here is my issue, I bought my 04 CTS 3.6L in October of last year, After about a month whenever I would stop at a light or even let the car Idle anywhere i could feel the engine like kicking while its idling like there is a leaky fuel injector. So I scanned it found no codes and then went on with life I decided to change the plugs and did so with the AC delcos, and that didn't solve it then one day it really kicked and flashed a CEL then I drove straight to auto zone and pulled a random misfire and a P0306 code so I changed the coil and plug in cylinder 6 and it has not come back on but still idling like crap and then somedays it runs great and others not so much. So i have been dealing with it trying to figure out what it is with two of my family members being ASE certified techs and one works for GM and has never heard of it being an ECM.. so I say ok just drive till code comes then... well today my gas gauge stopped working and lo and be hold everyone is saying it is a ECM.. so I need some help I can get an ecm already coded for my car for 300 bucks should I go for it? Is this the problem you think? I also called cadillac about the recall on them and they said the previous owner had it updated when it was recalled. I have changed the fuel filter as well and still runs like crap.. but then my family member ran the MAC scanner on it and it showed the history and it had p0301 Po303 and PO306 in the history. No Tranny codes, so What should I do any suggestions would be appreciated.

first thing that comes in my mind would be mass airflow sensor and you might check the air filter also

Air filter is fine, I was thinking it was the mass airflow but it seems everyone on this forum with this idling problem was fixed with a new ECM..

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Originally Posted by MoistCabbage

Who told you a faulty gas gauge points to a bad ECM??? Does it only do this at idle? Does it run mormally while driving? Clean the MAF, clean the TB.

An ASE certified technician that works for cadillac said it's another problem when a bad ECM starts to fail.

But the caddi has saddle tanks and my family member said it's one of those two lines that's having an issues and the gas gauge will get dropped according to alldata.

But I threw a bottle of techron in there and it came back to life.. My mechanic that I trust told me to try it and it worked..

it only does this when idling when I'm driving it seems to be ok but when I stop at a light or even sit idling it runs and you can feel it kick it will be fine then boom fine then boom and it's a constant thing it does not ever stop doing it..

I already cleaned the TB that helped it idle at 900 down to 600.. Cleaned the MAF it did nothing.. Maybe I should just replace it..

A mechanic I trust said that it may be a dripping fuel injector.. So I seafoamed it twice.. It was good for a little whole but still idled funny. I was thinking maybe I should get a complete fuel system cleaning professionally.

Re: Need help please!!!!! Any cadillac technicians!!!!

I would recommend a compression test for your idle problems. My 06 2.8l was doing the same thing and I came up with only 50lbs on cylinder 5. There is a test that will tell you if the bad gauge reading is the ECM. I am going to check my Seville sending unit when ever I get the time and I printed out the test for it to determine whether it is the sending unit the gauge or the ECM. It has to do with a voltage reading on a signal from the ECM. You will want to make sure before you replace your pump/sender. The pumps are a little pricey and hard to get at.